Method and apparatus for improving the quality of low grade fuel oils



Feb. 28, 1967 SAKON MORI 3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILSFiled Dec. 4, 1963 3 Sheets-Sheet 1 INVENTOR Feb. 28, 1967 SAKON MORl3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILSFiled Dec. 4, 1963 5 Sheets-Sheet 2 INVENTOR.

Am W

Feb. 28, 1967 SAKON MORI 3,306,828

METHOD AND APPARATUS FOR IMPROVING THE QUALITY OF LOW GRADE FUEL OILSFiled Dec. 4, 1963 3 Sheets-Sheet 5 INVENTOR.

BY lath M United States Patent 3,306,828 METHOD AND APPARATUS FORIMPROVING THE QUALITY OF LOW GRADE FUEL OILS Sakon Mori, 2394 Kugenuma,Fujisawa-shi, Kanagawa-ken, Japan Filed Dec. 4, 1963, Ser. No. 327,976 3Claims. (Cl. 196-46) The present invention relates to a method andapparatus for improving the quality of low grade fuel oils, moreparticularly low grade fuel oils for use in such fuel consumers asinternal combustion engines installed on the ship and vehicle, andboilers in steam electric power plants.

Heavy oils comm-only available on the market comprise mixtures of gasoil and residual still bottom fuel oil which is obtained by extractinggasoline, kerosene, gas oil and the like from crude mineral oil. InJapan heavy oils for use as fuel are classified into A fuel, B fuel andC fuel. Generally speaking, higher grade fuel oil contains more gas oiland lower grade fuel oil contains more residual still oil as isillustrated in the following table.

However, in practice, since the viscosity of the residual still bottomfuel oil varies depending upon the origin of the crude oils, theproportions of the ingredients of these mixtures are made somewhatdifferent from those illustrated in the above table taking inconsiderations such factors as viscosity and the like.

The price of low grade fuel oils such as C fuel containing highpercentages of residual still botto-m fuel is cheap. But such low gradefuel oils are infurious to internal combustion engines as well asboilers. More particularly, such low grade oils not only damage cylinderliners and piston rings of diesel engines, but also cause corrosion ofpreheaters for combustion air, economizers and other components ofboilers due to sulphur, vanadium and other impurities as well ascontamination or damage of heat receiving surfaces of boilers due toheavy carbon deposit and vanadium attack. It is also recognized that lowgrade fuel oils such as C fuel and the like containing high percentagesof residual still bottom fuel oil Will damage internal combustionengines and boilers due to moisture and other impurities contained inthe residual still bottom fuel oil.

It is very diflicult to remove moisture from low grade fuel oils,especially from those having a specific gravity of about 1.0 and highviscosity. Thus the moisture can not be well removed even when the fueloil is treated by a centrifugal separator. Also by using heat, themoisture cannot be removed unless the fuel oil is heated to atemperature above 100 C. But heating above 100 C. results in bad effectsupon cylinders and other components of internal combustion engines. Thusheating of fuel oils is limited to the boiling temperature of water (100C.) and heating to any higher temperature should be avoided in any case.

The Water that can be removed from fuel oils by centrifugal separatorsis contained in free state and the quantity thereof is small. Remainingwater is mainly contained in the particles of fuel oils as a suspension.Thus, a great number of heavy oil particles are suspended in residualstill bottom fuel oils. These oil particles comprise a coating ofrubbery or lacquer-like subst-ance around a particle of water, which maybe termed as an ice emulsion. Also such impurities as metal, sulphur andthe like are attached on said rubbery or lacquer like coating. Low gradefuel oils having hgh viscosity and high specific gravity, for examplethose having a specific gravity of higher than 0.98 and a viscosity ofmore than 1000 sec. when measured by Redwood No. 1 viscosimeter at 50C., cannot be purified by centrifugal separators. Moreover moisturecontained in such heavy oil particles cannot be removed by heating at atemperature below the boiling temperature of water C.).

There is also a method of removing water contained in low grade fueloils called as fuel oil treatment wherein a chemical agent is mixed withthem. However this method would merely render unstable the emulsifiedheavy oil particles but cannot impart any mechanical force to suchparticles.

The principal object of this invention is to improve the quality of alow grade fuel oil which contains essentially or a large quantity ofresidual still bottom fuel oil (for brevity, hereinafter the term lowgrade fuel oil means such oil) by a relatively simple physical means sothat it can be satisfactorily used as fuel for various consumer such asinternal combustion engines, boilers and gas turbines.

Another object of this invention is to separate and remove suchimpurities as moisture, iron, copper, vana dium, or other metals,sulphur, salts, asphalt, etc. contained in the low grade fuel oil by aphysical means whereby to improve its quality.

Still another object of this invention is to provide a novel apparatusof simple construction adapted to improve the quality of the low gradefuel oil.

Yet another object of this invention is to provide an apparatus forimproving the quality of the low grade fuel oil which has a novel oilcrusher adapted to destroy the so-called heavy oil particles consistingof nucleus of moisture contained in the fuel oil surrounded by rubberyor lacquer like material.

A further object of this invention is to provide a new apparatus forimproving the quality of the low grade fuel oil, which includes aprecipitating tank in which moisture and other impurities constitutingheavy oil particles that have been crushed are separated byprecipitation from th oil.

Still another object of this invention is to provide a novel apparatusfor improving the quality of the low grade fuel oil, which is compactand light weight suitable for mounting on ships and vehicles buteffective to continuously remove moisture and other impurities containedin said oil.

A still further object of this invention is to provide an apparatus forimproving the quality of the low grade fuel oil having a precipitationtank which can prevent the impurities which have been separated byprecipitationfrom said oil contained in said tank from being mixed againwith said purified oil due to vibration of vehicles or ships. Thus thisinvention contemplates to provide a method of and apparatus forpurifying low grade cheap fuel oil to suit for use asithe fuel for suchfuel consumers as internal combustion engines, boilers and gas turbineswithout any detrimental effect, whereby to save the cost of fuel. Whilethis invention can be applied to the purification of the fuel oils forinternal combustion engines, boilers and gas turbines of any kind, it ismost suitable for improving the quality of the fuel oil used on shipsand vehicles.

One feature of this invention resides in a process of improving thequality of a low grade fuel oil comprising the steps of heating said oilto a temperature within a range from 60 C. to the boiling point ofwater, applying a mechanical force to said fuel oil under heat todestroy heavy oil particles contained in said fuel oil, and separatingby precipitation moisture and other impurities comprising said oilparticles from said fuel oil.

Another feature of this invention resides in an apparatus for improvingthe quality of low grade fuel oil comprising means to heat said fueloil, an oil crusher which applies a mechanical force to said heated fueloil to destroy heavy oil particles contained therein, and aprecipitating tank wherein moisture and other impurities comprising saidheavy oil particles which have been destroyed are separated byprecipitation from said fuel oil by the difference in specificgravities.

For better understanding of the invention as well as other objects andfurther features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. 1 is a schematic representation of an apparatus for improving thequality of a low grade fuel oil, constructed according to thisinvention;

FIG. 2 is a plan view of an oil crusher used in FIG. 1;

FIG. 3 shows a vertical section of the oil crusher taken along the line3-3 of FIG. 2 and viewed in the direction indicated by arrows;

FIG. 4 shows a vertical section of a precipitating tank utilized in thisinvention;

FIG. 5 is a cross-sectional view of the precipitating tank taken alongthe line 55 of FIG. 4 and viewed in the direction indicated by arrows;and

FIG. 6 shows a vertical section of a modified precipitating tank.

Referring now to FIG. 1 of the accompanying drawings, there isillustrated a schematic diagram of an apparatus which is to be mountedon ships to improve the quality of a low grade fuel oil for continuouslysupply purified oil to a diesel engine or a boiler on said ship.

The apparatus shown in FIG. 1 comprises an oil tank or reservoir 31, anoil feed pump 32, an oil heater 33, an oil crusher 34 and aprecipitating tank 35. Low grade oil contained in the tank 31 is fed tothe oil heater 33 by the oil feed pump 32 via conduits 37 and 38. Theoil heater 33 is provided with a heating coil which is supplied withsteam from a steam boiler 40 mounted on the ship. The fuel oil from theoil heater is conveyed to the oil crusher 34, which will be described inmore detail hereinunder, by a second oil feed pump 42 through conduits41 and 43. Emulsified heavy oil particles contained in the fuel oil aredestroyed by the crusher and then sent via a conduit 44 to theprecipitating tank 35 in which destroyed moisture, rubbery substance andother impurities which have been comprised in said heavy oil particlesare separated by precipitation from the main body of the fuel oil.

As diagrammatically shown in FIG. 1, the precipitating tank 35 isprovided with an internal heating coil connected to the boiler 40. Thepurified fuel oil is supplied from the precipitating tank 35 to a mainengine, for example, a diesel engine 36 via a conduit 47, by means of asuitable pump, not shown, or by gravity. The purpose of the oil heater33 is to heat the fuel oil to a temperature which is effective to bringthe fuel oil to an unstable condition in which it can be more easilydestroyed by the crushers, and the heating coil 45 serves to lower theviscosity of the fuel oil to aid precipitation of said impurities.

As has been described hereinbefore, many heavy oil particles aresuspended in a residual still bottom fuel oil or a low grade fuel oilcontaining it in a large quantity. Each of these particles comprises anucleus of moisture, a film of rubbery or lacquer-like substancecovering said nucleus and copper, iron, vanadium or other metals,sulphur, salts or other impurities adhering to said film. Such heavy oilparticles can not be separated by treating them with a centrifugalseparator. However when heated they will become unstable and can bedestroyed easily. Thus by merely heating them to a temperature below theboiling temperature of water, they can be destroyed by shearing,compressive or percussive force. Therefore in accordance with thisinvention the heavy oil particles contained in a low grade fuel oil aredestroyed by subjecting them to the shearing, compression or percussionaction afforded by said oil crusher. When these oil particles aredestroyed, their films are broken to release particles of moisturecontained therein. These particles of moisture are coagulated to haverelatively large diameters by the agitating motion imparted to the fueloil by the crusher. Since the specific gravity of water is larger thanthat of the fuel oil coagulated water particles will precipitate in theprecipitating tank. Thus, the moisture content as well as the specificgravity of the upper portion of the fuel oil in the precipitating tankwill be decreased, and the destroyed rubbery films and impuritiesattached thereon are also precipitated as a sludge, thus purifying thefuel oil. Purified fuel oil of improved quality can then be supplied todiesel engines, boilers or gas turbines and can be used therein withoutany deleterious effects mentioned above.

Heating of said fuel oil results in the instability of the heavy oilparticles so that they can be easily destroyed, and when the temperatureof the fuel oil is lowered formation of said sludge is increased.Therefore by repeating said cycle of operations, the quality and purityof the fuel oil can be greatly improved.

It was found by experiment that the amount of said sludge and otherimpurities was only 0.1 to 0.3%, by weight, based on the total weight ofthe fuel oil and that fuel oils that contain 0.3% of sludge andimpurities are relatively rare, so that removal of these sludge andimpurities does not mean any substantial loss of the fuel oil and thegain provided by improved quality is much larger than such loss. Alsoreduction of the moisture content to the minimum greatly enhancesdevelopment of the total potential heat energy of the fuel oil andminimizes the amount of negative work done due to absorption of latentheat by the moisture.

As mentioned above while the temperature to which the fuel oil is heatedshould be lower than the boiling point of water, at temperaturesslightly higher than room temperature destruction of the heavy oilparticles are not effective as expected. There-fore it is necessary toheat the fuel oil to at least 60 C. and the more its temperature isclose to the boiling point of water the easier the destruction of theheavy oil particles becomes.

When one cycle of operation involving destroy of the heavy oil particlesand subsequent separation by precipitation of the components of saidparticles is not sufficient to purify the fuel oil to the desiredextent, a plurality of oil crushers and precipitating tanks may bearranged in series between the oil tank and the fuel consumer such as adiesel engine and the precipitating tank closest to the diesel enginemay be used as the daily service tank.

As shown in FIG. 1, a drain pipe 61 is connected to the bottom of theprecipitating tank 35. The drain pipe 61 is connected to a water drainpipe 62 leading to a bilge well 66 and a sludge drain pipe 63 leading toa dirty oil tank 67, respectively through valves 64 and 65. As water andsludge accumulate in the bottom of the precipitating tank 35, waterconstitutes the bottom layer since it is heavier than sludge, so that atfirst the valve 64 is opened to drain the water into the bilge well 66and then the valve 65 is opened to drain the sludge into the dirty oiltank 67 together with dirty oil in the bottom portion of theprecipitating tank 35. When water, sludge and dirty oil are completelydrained the valve 65 is closed.

As shown in FIGS. 2 and 3, the oil crusher 34 comprises an upper casing101, a lower casing 102, and a pair of relatively rotating disks 103 and104. The upper casing is an inverted dish shape having a cylindricalboss 107 at its top having a vertical bore 108 therein. A vertical inletpipe 109 is connected to the center of the stationary disk 103, thelower end of the inlet pipe 109 being connected to a shallow funnel likerecess 110 and 111a provided at the lower surface of the disk 103, whilethe upper end thereof being connected to the conduit 43 by a joint .137in fluid tight relationship thereto. The stationary disk 103 is screwedat 109a to the upper casing 101 and a packing means 113 is provided inthe bore 108 to surround the inlet pipe 109. A cup-shaped casing 102 ishermetically connected to the upper casing 101 by their flanges 105 and118, a packing 130 and a plurality of bolts 131 positively held by meansof nuts 132. The rotary disk 104 is journaled on the upper surface ofthe casing 102 and is driven by an electric motor 136 con nected to thelower portion 129 of a shaft 126 which is hermetically sealed in theboss 120 by means of a packing means 127, said 'boss 120 being providedwith a central vertical bore 121. As stated above the lower surface ofthe stationary disk 103 is slightly recessed so that the width of thegap 134 between the disks is about 1 to 3 mm. near the center butdecreases toward the periphery. The conduit 44 lea-ding to theprecipitating tank 35 is connected to an annular space 135 surroundingthe periphery of the disks 103 and 104 by means of flanges 123, 144 anda conduit 122. Heated low grade fuel oil supplied through the conduit 43and the inlet pipe 109 enters into the center of the (gap 134 and thenthrown radially by the rotary disk 104. While passing through theperipheral portions of the disks 103 and 104 which are in slidingcontact the fuel oil is subjected to the crushing action to destroy theheavy oil particles contained therein. The heavy oil particles are alsodestroyed when they are thrown against the surrounding walls of theupper and lower casings by the centrifugal force. The fuel oilcontaining the destroyed heavy oil particles is discharged into theprecipitating tank 35 where the released particles of moisture coagulateinto larger droplets and precipitate together with the sludge asdescribed above.

Since the oil crusher applies to the low grade fuel oil four forces ofshear, compression, impact and acceleration, the heavy oil particles aredestroyed positively. Moreover as this oil crusher discharges thetreated oil by centrifugal force, the capacity of the feed pump 42 maybe decreased, or this :pump may be omitted, if desired. Thus the oilcrusher is especially suitable for use is diesel engines of largehorsepower rating which consume relatively large quantities of low gradefuel oil containing high percentage of residual still bottom fuel oiland having relatively large viscosity. In addition, by providingsuitable coarse surfaces on the opposing but not contacting inner facesof the disks 103 and 104, it is possible to impart turbulent motion tothe treated oil, thus improving the efficiency of the crusher.

It should be understood that this invention is not limited to the use ofthe oil crusher of the type illustrated, but a centrifugal separator ofany suitable design may be used provided that it can impart to the heavyoil particles enough shearing, compressing and/ or impact forcessufficient to destroy them.

Referring now to FIGS. 4 and 5, the precipitating tank 35 comprises amain body 202 of circular or square cross section, a cover 203 havingsaid conduit 44, a conical bottom 206 and a receiver 209 forprecipitating impurities. This receiver also has a funnel shape andtelescoped over the lower end of the conical bottom 206. A conduit 47leading to the fuel consumer opens in the lower portion of the main body202 and a steam coil 45 is positioned beneath the conduit 47. As alreadydescribed in connection with FIG. 1 the receiver is connected with thewater drain pipe 62 and the sludge drain pipe 63 through valves 64 and65, respectively. It was found desirable to design the angle of subtenda of the conical bottom 206 to have a value less than 90.

In operation, the fuel oil treated by the oil crusher is discharged intothe main body 202 wherein it is heated to a suitable temperature by saidsteam coil 45 to cause particles of moisture to coagulate andprecipitate together with the sludge. The precipitated water and sludgewill enter in the receiver through an opening 204 and will beaccumulated therein with the layer of water at the bottom. Since thereceiver 211 is not affected by the convection caused by the heatingcoil 45, there is no fear that precipitated impurities are again mixedwith the body of fuel oil contained in the main body 202. As previouslydescribed, at first collected water is drained by opening the valve 64and thereafter the sludge is drained by opening the value 65.

FIG. 6 shows a modified precipitating tank with a modified bottomportion from that shown in FIG. 4. For brevity, corresponding parts ofFIG. 4 are designated by the same reference numerals and descriptionthereof is omitted. In FIG. 6 the lower end of the conical portion 206is connected to the funnel shaped receiver 211 via a relatively longtube 251. The operation of the precipitating tank shown in FIG. 6 issimilar to that shown in FIG. 4, but with long connecting tube 251, itis more difficult for the collected impurities in the receiver 211 toflow back into the main body 202 upon rolling and pitching of the ship.If desired, the conical bottom 206 may be lined with smooth plate ofstainless and the like in order to assure positive falling of theimpurities having high viscosity and large adhesive force. Tests made onsaid B fuel by using the apparatus shown in FIGS. 2 through 5 showedthat the purity and quality of the fuel were improved as shown in thefollowing table.

It was found that the capacity of the precipitating tank may be madesmall, of the order of 2 to 3 tons for ships equipped with a dieselengine of 12,000 horsepower and where two precipitating tanks arecascaded with the last one serving also as the daily service tank, thecapacity thereof may be made small enough to store fuel oil of theamount corresponding to 6 hours when they are used for a diesel enginewhich consumes 40 tons of fuel per 24 hours in order to develop 12,000hoursepower. Even for the bunker C fuel oil which is available in NewYork and having a property similar to that of tar oil the capacity ofthe daily service tank was only 15 tons.

An embodiment of this invention comprising three oil crushers and threeprecipitating tanks connected in series was actually tested on twoships, each 10,000 shipping tons. More particularly, a low grade fueloil of Venezuela origin having a viscosity of 1500 seconds when testedat 50 C. by a Redwood No. 1 viscosity meter and a specific gravity of0.98 to 0.99 was used in the diesel engines of said two ships. Waterranging from to 423 liters was removed per 10 kiloliters of the fueloil. Although the quantity of the sludge removed was not actuallymeasured, substantial quantity thereof was removed. As the result, thespecific gravity was decreased while at the same time the viscosity wasalso decreased to below 1000 seconds when measured at 50 C. by RedwoodNo.' 1 viscosity meter so that the oil became satisfactory fuel.

While the method and apparatus have been described with reference tospecific embodiments thereof, it will be clear to those skilled in theart that this invention can be embodied in various ways within the scopeand spirit of the invention as defined in the appended claims. Forexample, electric energy or exhaust gas of an internal engine or thelike consuming the processed fuel oil may be used to heat the low gradefuel oil instead of steam. However, steam is preferred to purify thefuel oil to be used in steam electric power plants or on ship from thestandpoint of cost down. Use of exhaust gas of the main engine isadvantageous for small ships as fishing boats. In addition the number,capacity and configuration of the precipitating tank may be varieddependent upon the size of fuel consumers (fuel consumption) and type ofthe fuel oil used. When applied to ships, a cooling device may beprovided for the receiver of the precipitated impurities in order toincrease the viscosity of the sludge, thus positively preventing thereverse flow of the precipitated impurities. In the modification shownin FIGS. 6 and 7, it may be possible to utilize the connecting tube 251as the receiver for the precipitated impurities whereby to omit thereceiver 211. Where the apparatus of this invention is used in steamelectric power plants such mechanism for preventing reverse flow may beomitted. Also the precipitating tank and the daily service tank are notrequired to be installed in the same place as in the conventionalpractice.

This invention can be advantageously used for various internalcombustion engines or boilers installed on ships of various size,trains, automobiles, or in steam electric power stations and the like tocontinuously purify the fuel oil and to save the cost thereof.

What is claimed is:

1. In an apparatus for supplying improved fuel oil from low grade fueloil wherein oil in an oil tank is pumped through an oil heater to an oilcrusher and delivered to a precipitation tank, the water and impuritiesbeing separated therein and drained out by precipitation from the mainbody of fuel oil, while the improved fuel oil is supplied to utilizationmeans, the improvement therein wherein said oil crusher comprises, firstconduit means leading to said oil heater; upper and lower dishshapedoutwardly flanged casing halves, fastened together at the flangesforming a crushing chamber; an upper stationary disc in said chamberwith a slightly recessed center, said recess decreasing towards theperiphery thereof; a vertically disposed inlet pipe leading from saidconduit means to said upper stationary disc recessed center; a lowerrotating disc in said chamber in crushing engagement with said upperstationary disc, including means to rotate said lower disc; a peripheraloutlet from said upper and lower discs including second conduit meansleading to the upper portion of said precipitation tank; and, saidprecipitation tank including an elongated main chamber with a conicalbottom with a heating coil towards the lower portion of said mainchamber and an outlet feed pipe to said utilization means from said mainchamber.

2. In an apparatus as claimed in claim 1, said precipitation tankincluding a receiver for the impurities telescoped over the conicalbottom thereof.

3. In an apparatus as claimed in claim 1, said precipitation tankincluding a long tube connected at the upper end to said conical bottomand at its lower end to a funnel shaped receiver for the impurities.

References Cited by the Examiner UNITED STATES PATENTS 2,862,876 12/1958Winberg 208370 FOREIGN PATENTS 591,743 4/1925 France.

ALPHONSO D. SULLIVAN, Primary Examiner.

1. IN AN APPARATUS FOR SUPPLYING IMPROVED FUEL OIL FROM LOW GRADE FUELOIL WHEREIN OIL IN AN OIL TANK IS PUMPED THROUGH AN OIL HEATER TO AN OILCRUSHER AND DELIVERED TO A PRECIPITATION TANK, THE WATER AND IMPURITIESBEING SEPARATED THEREIN AND DRAINED OUT BY PRECIPITATION FROM THE MAINBODY OF FUEL OIL, WHILE THE IMPROVED FUEL OIL IS SUPPLIED TO UTILIZATIONMEANS, THE IMPROVEMENT THEREIN WHEREIN SAID OIL CRUSHER COMPRISES, FIRSTCONDUIT MEANS LEADING TO SAID OIL HEATER; UPPER AND LOWER DISHSHAPEDOUTWARDLY FLANGED CASING HALVES, FASTENED TOGETHER AT THE FLANGESFORMING A CRUSHING CHAMBER; AN UPPER STATIONARY DISC IN SAID CHAMBERWITH A SLIGHTLY RECESSED CENTER, SAID RECESS DECREADING TOWARDS THEPERIPHERY THEREOF; A VERTICALLY DISPOSED INLET PIPE LEADING FROM SAIDCONDUIT MEANS TO SAID UPPER STATIONARY DISC RECESSED CENTER; A LOWERROTATING DISC IN SAID CHAMBER IN CRUSHING ENGAGEMENT WITH SAID UPPERSTATIONARY DISC, INCLUDING MEANS TO ROTATE SAID LOWER DISC; A PERIPHERALOUTLET FROM SAID UPPER AND LOWER DISCS INCLUDING SECOND CONDUIT MEANSLEADING TO THE UPPER PORTION OF SAID PRECIPITATION TANK; AND, SAIDPRECIPITATION TANK INCLUDING AN ELONGATED MAIN CHAMBER WITH A CONICALBOTTOM WITH A HEATING COIL TOWARDS THE LOWER PORTION OF SAID MAINCHAMBER AND AN OUTLET FEED PIPE TO SAID UTILIZATION MEANS FROM SAID MAINCHAMBER.